1. Field of the Invention
The present invention relates to a circulating memory apparatus and an image storage and distribution system suitable for storing time series data, or in particular to a circulating memory apparatus and an image storage and distribution system suitable for storing a plurality of series of image data.
2. Description of the Related Art
In a remote monitor system, image data picked up sequentially by image pickup devices such as Web cameras, i.e. image data input in time series from a plurality of sites are stored (recorded or held) in a magnetic disk (such as a hard disk), an optical disk or a semiconductor disk or the like large-capacity recording device, while at the same time distributing the images through a network, so that they can be monitored on the monitor screen at a remote place.
The image data recording device is limited in capacity. The monitor system of this type, therefore, employs a circulating recording method, in which the memory area secured in the recording device is used in circulation and the oldest image data in time series are rewritten sequentially by the latest image data. This method makes it possible to hold and reproduce a predetermined amount of past image data. Several well-known techniques are available to manage the memory addresses in the circulating memory apparatus of this type. The technique disclosed in JP-A-11-232842 (FIGS. 1 to 12) is an example.